According to the reference book The Worlds of the Federation (p. 36), the Rigel system and the Orion system are one and the same. Rigel VIII being the homeworld of the Orion species. According to the book, Rigel II and Rigel IV were colonized by Humans. According to Star Trek Maps (Chart D), the Rigel system was located around the real star Beta Orionis. The chart also references Rigel VIII as the planet Orion.